Canvas resize option allows you to alter the height, idth and measurement of an image. The other thing to look at in the title-bar is the mode. You can right click on the image to open the menu, or use the menu along the top of the Image window.
For this task we are going to use the Scale Tool, which is located on the Toolbox. Set the Canvas Size, Offset and Layers options as per your requirements and finally click the Resize button. Then a box named Set Image Canvas Size gets displayed and you can view the Preview of the image in this box itself. There you can enter Width and Height parameters. Below are some tables I was able to find while searching the web, how to size image in gimp. The concept acting in the public interest. So, click on it select it and then click on the image, this will make the Scale dialogue box to appear. I verify this by inserting the image into Goo. You can also put on a tight-fitting roasting pan lid, but the glaze may take longer to crystallize. Click File Open and navigate to the area where you have stored the image you plan to use for your first layer.